diff --git a/public_html/lists/admin/admin.php b/public_html/lists/admin/admin.php
index 557cef1ba..9808aa721 100644
--- a/public_html/lists/admin/admin.php
+++ b/public_html/lists/admin/admin.php
@@ -102,7 +102,7 @@
             'statistics'  => !empty($_POST['statistics']),
             'settings'    => !empty($_POST['settings']),
         );
-        Sql_Query(sprintf('update %s set modified=now(), modifiedby = "%s", privileges = "%s" where id = %d',
+        Sql_Query(sprintf('update %s set modifiedby = "%s", privileges = "%s" where id = %d',
             $GLOBALS['tables']['admin'], adminName($_SESSION['logindetails']['id']), sql_escape(serialize($privs)),
             $id));
 
diff --git a/public_html/lists/admin/inc/userlib.php b/public_html/lists/admin/inc/userlib.php
index da8eb273c..f417ca9fb 100644
--- a/public_html/lists/admin/inc/userlib.php
+++ b/public_html/lists/admin/inc/userlib.php
@@ -203,7 +203,7 @@ function addNewUser($email, $password = '')
     $blacklist = isBlackListed($email);
     $passwordEnc = encryptPass($password);
     Sql_Query(sprintf('insert into %s set email = "%s", blacklisted = "%d",
-    entered = now(),modified = now(),password = "%s",
+    entered = now(),password = "%s",
     passwordchanged = now(),disabled = 0,
     uniqid = "%s",htmlemail = 1, uuid = "%s"
     ', $GLOBALS['tables']['user'], sql_escape($email), $blacklist, $passwordEnc, getUniqid(), (string) uuid::generate(4)));
diff --git a/public_html/lists/admin/initialise.php b/public_html/lists/admin/initialise.php
index 35a5b5b05..c739709a8 100644
--- a/public_html/lists/admin/initialise.php
+++ b/public_html/lists/admin/initialise.php
@@ -167,8 +167,8 @@ function output($message)
                 $_SESSION['firstinstall'] = 1;
                 $adminemail = $_REQUEST['adminemail'];
                 $adminpass = $_REQUEST['adminpassword'];
-                Sql_Query(sprintf('insert into %s (loginname,namelc,email,created,modified,password,passwordchanged,superuser,disabled)
-                    values("%s","%s","%s",now(),now(),"%s",now(),%d,0)',
+                Sql_Query(sprintf('insert into %s (loginname,namelc,email,created,password,passwordchanged,superuser,disabled)
+                    values("%s","%s","%s",now(),"%s",now(),%d,0)',
                     $tables['admin'], 'admin', 'admin', sql_escape($adminemail), encryptPass($adminpass), 1));
 
                 //# let's add them as a subscriber as well
diff --git a/public_html/lists/admin/messages.php b/public_html/lists/admin/messages.php
index 880cdd444..4ffb2262f 100644
--- a/public_html/lists/admin/messages.php
+++ b/public_html/lists/admin/messages.php
@@ -215,9 +215,9 @@
     $idToDuplicate = sprintf('%d', $_GET['duplicate']);
     $action_result .= $GLOBALS['I18N']->get('Copying')." $idToDuplicate ..";
     Sql_Query(sprintf('insert into %s (uuid, subject, fromfield, tofield, replyto, message, textmessage, footer, entered,
-        modified, embargo, repeatuntil, repeatinterval, requeueinterval, status, htmlformatted, sendformat, template, rsstemplate, owner)
+        embargo, repeatuntil, repeatinterval, requeueinterval, status, htmlformatted, sendformat, template, rsstemplate, owner)
         select "%s", subject, fromfield, tofield, replyto, message, textmessage, footer, now(),
-        now(), now(), now(), repeatinterval, requeueinterval, "draft",  htmlformatted,
+        now(), now(), repeatinterval, requeueinterval, "draft",  htmlformatted,
         sendformat, template, rsstemplate, "%d" from %s
         where id = %d',
         $GLOBALS['tables']['message'], (string) Uuid::generate(4), $_SESSION['logindetails']['id'],$GLOBALS['tables']['message'],
diff --git a/public_html/lists/admin/structure.php b/public_html/lists/admin/structure.php
index 703f3e9c1..69ccfce78 100644
--- a/public_html/lists/admin/structure.php
+++ b/public_html/lists/admin/structure.php
@@ -46,7 +46,7 @@
         'optedin'         => array('tinyint default 0', 'sysexp:Did this subscriber manually confirm'),
         'bouncecount'     => array('integer default 0', 'sysexp:Number of bounces'),
         'entered'         => array('datetime', 'sysexp:Entered'),
-        'modified'        => array('timestamp', 'sysexp:Last Modified'),
+        'modified'        => array('timestamp not null default current_timestamp on update current_timestamp', 'sysexp:Last Modified'),
         'uniqid'          => array('varchar(255)', 'sysexp:Unique ID'),
         'uuid'            => array('varchar(36) default ""', 'sys:UUID'),
         'htmlemail'       => array('tinyint default 0', 'Send this subscriber HTML emails'),
@@ -89,7 +89,7 @@
         'listorder'   => array('integer', 'Order of listing'),
         'prefix'      => array('varchar(10)', 'Subject prefix'),
         'rssfeed'     => array('varchar(255)', 'Rss Feed'),
-        'modified'    => array('timestamp', 'Modified'),
+        'modified'    => array('timestamp not null default current_timestamp on update current_timestamp', 'Modified'),
         'active'      => array('tinyint', 'Active'),
         'owner'       => array('integer', 'Admin who is owner of this list'),
         'category'    => array('varchar(255) default ""', 'List category'),
@@ -108,7 +108,7 @@
         'userid'      => array('integer not null', 'Subscriber ID'),
         'listid'      => array('integer not null', 'List ID'),
         'entered'     => array('datetime', 'Entered'),
-        'modified'    => array('timestamp', 'Modified'),
+        'modified'    => array('timestamp not null default current_timestamp on update current_timestamp', 'Modified'),
         'primary key' => array('(userid,listid)', 'Primary Key'),
         'index_1'     => array('userenteredidx (userid,entered)', ''),
         'index_2'     => array('userlistenteredidx (userid,listid,entered)', ''),
@@ -126,7 +126,7 @@
         'textmessage'     => array('longtext', 'Text version of Message'),
         'footer'          => array('text', 'Footer for a message'),
         'entered'         => array('datetime', 'Entered'),
-        'modified'        => array('timestamp', 'Modified'),
+        'modified'        => array('timestamp not null default current_timestamp on update current_timestamp', 'Modified'),
         'embargo'         => array('datetime', 'Time to send message'),
         'repeatinterval'  => array('integer default 0', 'Number of seconds to repeat the message'),
         'repeatuntil'     => array('datetime', 'Final time to stop repetition'),
@@ -163,7 +163,7 @@
         'messageid' => array('integer not null', 'Message ID'),
         'listid'    => array('integer not null', 'List ID'),
         'entered'   => array('datetime', 'Entered'),
-        'modified'  => array('timestamp', 'Modified'),
+        'modified'  => array('timestamp not null default current_timestamp on update current_timestamp', 'Modified'),
         'unique_1'  => array('(messageid,listid)', ''),
         'index_1'   => array('listmessageidx (listid,messageid)', ''),
     ),
@@ -223,7 +223,7 @@
     'sendprocess' => array( // keep track of running send processes to avoid to many running concurrently
         'id'        => array('integer not null primary key auto_increment', 'ID'),
         'started'   => array('datetime', 'Start Time'),
-        'modified'  => array('timestamp', 'Modified'),
+        'modified'  => array('timestamp not null default current_timestamp on update current_timestamp', 'Modified'),
         'alive'     => array('integer default 1', 'Is this process still alive?'),
         'ipaddress' => array('varchar(50)', 'IP Address of who started it'),
         'page'      => array('varchar(100)', 'The page that this process runs in'),
@@ -261,7 +261,7 @@
         'user'    => array('integer not null', 'subscriber ID'),
         'message' => array('integer not null', 'Message ID'),
         'bounce'  => array('integer not null', 'Bounce ID'),
-        'time'    => array('timestamp', 'When did it bounce'),
+        'time'    => array('timestamp not null default current_timestamp on update current_timestamp', 'When did it bounce'),
         'index_1' => array('umbindex (user,message,bounce)', 'index'),
         'index_2' => array('useridx (user)', 'index'),
         'index_3' => array('msgidx (message)', 'index'),
@@ -273,7 +273,7 @@
         'message' => array('integer not null', 'Message ID'),
         'forward' => array('varchar(255)', 'Forward email'),
         'status'  => array('varchar(255)', 'Status of forward'),
-        'time'    => array('timestamp', 'When was it forwarded'),
+        'time'    => array('timestamp not null default current_timestamp on update current_timestamp', 'When was it forwarded'),
         'index_1' => array('usermessageidx (user,message)', 'index'),
         'index_2' => array('useridx (user)', 'index'),
         'index_3' => array('messageidx (message)', 'index'),
@@ -290,7 +290,7 @@
         'namelc'          => array('varchar(255)', 'sys:Normalised loginname'),
         'email'           => array('varchar(255) not null', 'Email'),
         'created'         => array('datetime', 'sys:Time Created'),
-        'modified'        => array('timestamp', 'sys:Time modified'),
+        'modified'        => array('timestamp not null default current_timestamp on update current_timestamp', 'sys:Time modified'),
         'modifiedby'      => array('varchar(66)', 'sys:Modified by'),
         'password'        => array('varchar(255)', 'sys:Password'),
         'passwordchanged' => array('date', 'sys:Last time password was changed'),
diff --git a/public_html/lists/admin/upgrade.php b/public_html/lists/admin/upgrade.php
index b10e9697b..7a849a6e2 100644
--- a/public_html/lists/admin/upgrade.php
+++ b/public_html/lists/admin/upgrade.php
@@ -468,6 +468,34 @@ function output($message)
         Sql_Query("alter table {$GLOBALS['tables']['admin']} modify modifiedby varchar(66) default ''");
     }
 
+    if (version_compare($dbversion, '3.6.15', '<')) {
+        // Ensure timestamp field does not have null values then give explicit defaults
+        Sql_Query(sprintf('update %s set modified = created where modified is null', $GLOBALS['tables']['admin']));
+        Sql_Query(sprintf('update %s set modified = entered where modified is null', $GLOBALS['tables']['list']));
+        Sql_Query(sprintf('update %s set modified = entered where modified is null', $GLOBALS['tables']['listmessage']));
+        Sql_Query(sprintf('update %s set modified = entered where modified is null', $GLOBALS['tables']['listuser']));
+        Sql_Query(sprintf('update %s set modified = entered where modified is null', $GLOBALS['tables']['message']));
+        Sql_Query(sprintf('update %s set modified = started where modified is null', $GLOBALS['tables']['sendprocess']));
+        Sql_Query(sprintf('update %s set modified = entered where modified is null', $GLOBALS['tables']['user']));
+        Sql_Query(sprintf('update %s set time = current_timestamp where time is null', $GLOBALS['tables']['user_message_bounce']));
+        Sql_Query(sprintf('update %s set time = current_timestamp where time is null', $GLOBALS['tables']['user_message_forward']));
+
+        foreach (['admin', 'list', 'listmessage' , 'listuser', 'message', 'sendprocess', 'user'] as $t) {
+            Sql_Query(sprintf(
+                'alter table %s modify modified timestamp not null default current_timestamp on update current_timestamp',
+                $GLOBALS['tables'][$t]
+            ));
+        }
+        Sql_Query(sprintf(
+            'alter table %s modify time timestamp not null default current_timestamp on update current_timestamp',
+            $GLOBALS['tables']['user_message_bounce']
+        ));
+        Sql_Query(sprintf(
+            'alter table %s modify time timestamp not null default current_timestamp on update current_timestamp',
+            $GLOBALS['tables']['user_message_forward']
+        ));
+    }
+
     //# longblobs are better at mixing character encoding. We don't know the encoding of anything we may want to store in cache
     //# before converting, it's quickest to clear the cache
     clearPageCache();
diff --git a/public_html/lists/index.php b/public_html/lists/index.php
index 10b00fd05..cc6277a1b 100644
--- a/public_html/lists/index.php
+++ b/public_html/lists/index.php
@@ -1145,8 +1145,8 @@ function forwardPage($id)
                             sendAdminCopy(s('Message Forwarded'),
                                 s('%s has forwarded message %d to %s', $userdata['email'], $mid, $email),
                                 $messagelists);
-                            Sql_Query(sprintf('insert into %s (user,message,forward,status,time)
-                 values(%d,%d,"%s","sent",now())',
+                            Sql_Query(sprintf('insert into %s (user,message,forward,status)
+                 values(%d,%d,"%s","sent")',
                                 $tables['user_message_forward'], $userdata['id'], $mid, $email));
                             if ($iCountFriends) {
                                 ++$nFriends;
@@ -1156,8 +1156,8 @@ function forwardPage($id)
                             sendAdminCopy(s('Message Forwarded'),
                                 s('%s tried forwarding message %d to %s but failed', $userdata['email'], $mid, $email),
                                 $messagelists);
-                            Sql_Query(sprintf('insert into %s (user,message,forward,status,time)
-                values(%d,%d,"%s","failed",now())',
+                            Sql_Query(sprintf('insert into %s (user,message,forward,status)
+                values(%d,%d,"%s","failed")',
                                 $tables['user_message_forward'], $userdata['id'], $mid, $email));
                             $ok = false;
                         }